Field of the Invention
The invention relates to an illumination system and a projection apparatus.
Description of Related Art
In a framework of a laser projector, generally, a blue laser light is applied to sequentially irradiate a phosphor layer and a reflection region of a phosphor wheel to output a yellow light and a blue light, and then a filter element in the projector is applied to extract a required color light from wide-waveband yellow light, and the extracted color light enters a light valve. However, the part of the un-extracted light is reflected by the filter element and transmitted back to the phosphor layer of the phosphor wheel along the coming path of the yellow light, and the phosphor layer may absorb the part of the un-extracted light, resulting in a temperature rise, which may further result in a conversion efficiency reduction of the phosphor layer due to heat. Further, if the projector is used for a long time, the temperature of the phosphor layer exceeds its affordable temperature range, and it may be burned black. The above situation may result in poor reliability of the projector, or even failure of the projector.
The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.